Blue Phoenix - Chapter 44: Disqualified?

When Kim Seojin opened his eyes, he found himself three hundred years in the future.In the last three hundred years, humanity went through a lot of changes. Science had developed, cities became more modern, and space travel became a reality. But all of that came at a cost.The world had become a plaything of gods. Every year, humans were selected to represent their race in a devilish game, all for the entertainment of the gods.Kim Seojin was one of the thousand people selected in a timeline where he didn't belong.There was one more person. A Regressor burdened with the memories of countless failed timelines and the knowledge of the destruction to come, was also a part of the game…

I found myself inside the game I used to enjoy.But something feels off.

In the middle of a deserted island, a small boy wakes up with two sets of memories: one from his few years of life and the other from a man who lived to adulthood and achieved great things. When he least expected it, a powerful master appeared on the island and took him in as a disciple, revealing a shocking fact: magic exists in that world, and, thanks to it, humanity managed to conquer the galaxy.

Zheng Tan somehow returns to the year 2003, turning into a black cat. Picked up from a rubbish heap by the Jiao family, he is given the name “Charcoal”, and so begins the life inside Professor Jiao’s family. Zheng Tan remembers that he was once a person, but currently his body is that of a cat. He has no way of speaking the human language, but can understand it, and even retains the thinking and IQ of a young 20 year old youth. Read along as he adapts to this new world, and somehow tumbles from a group brawl to catching a thief.

- Description from Novelupdates